Memory system

Abstract

According to one embodiment, a memory system includes a memory, and a processor. The memory converts an amount of charge held by a memory cell into a value. The processor executes a first process of reading first data from the memory. The processor executes a second process of reading the first data by making the memory use a first determination potential different in a case where error correction of the first data read through the first process is failed. The processor executes a third process of reading second data from the memory by making the memory use a third determination potential in a case where error correction of the first data read through the second process is succeeded. The third determination potential is the first determination potential used by the memory in a case where error correction of the first data read through the second process is succeeded.

What is claimed is: 
     
       1. A memory system comprising:
 a memory configured to be written data therein, the memory being capable of changing a potential used for determination of the data in reading of the data; 
 a controller configured to read first data from the memory by making the memory use a first potential, execute error detection and correction of the first data read from the memory by using the first potential, read the first data from the memory by making the memory use a second potential, execute error detection and correction of the second data read from the memory by using the second potential differing from the first potential, and make the memory use a third potential in reading second data from the memory in a case where the error detection and correction of the first data read by using the third potential is successful, the third potential being the first potential or the second potential, wherein 
 the memory includes multiple block groups, 
 each of the multiple block groups includes one or more blocks, 
 each of the one or more blocks is a unit of erase, and 
 the controller stores information relating to the third potential for each of the multiple block groups. 
 
     
     
       2. The memory system according to  claim 1 , wherein, after error detection and correction of the first data read by using the first potential is failed, the controller read the first data from the memory by making the memory use the second potential. 
     
     
       3. The memory system according to  claim 2 , wherein the controller executes refresh of the first data at least on the basis of whether or not error detection and correction of the first data read by using the second potential is failed. 
     
     
       4. The memory system according to  claim 3 , wherein the controller read the first data from the memory by making the memory use the first potential periodically. 
     
     
       5. The memory system according to  claim 1 , wherein
 each of the multiple block groups includes two or more blocks, and 
 the controller accesses the two or more blocks included in a same block group among the multiple block groups in parallel. 
 
     
     
       6. The memory system according to  claim 5 , wherein
 the memory includes first and second chips, 
 the two or more blocks included in the same block group includes a first block and a second block, 
 the first chip includes the first block, and 
 the second chip includes the second block. 
 
     
     
       7. A method for reading data from a memory by making the memory use a potential, the memory including multiple block groups, each of the multiple block groups including one or more blocks, each of the one or more blocks being a unit of erase, the method comprising:
 reading first data from the memory by making the memory use a first potential; 
 executing error detection and correction of the first data read from the memory by using the first potential; 
 reading the first data from the memory by making the memory use a second potential differing from the first potential; 
 executing error detection and correction of the second data read from the memory by using the second potential; and 
 making the memory use a third potential in reading second data from the memory in a case where the error detection and correction of the first data read by using the third potential is successful, the third potential being the first potential or the second potential, wherein 
 the method further comprising storing information relating to the third potential for each of the multiple block groups. 
 
     
     
       8. The method according to  claim 7 , wherein the reading the first data from the memory by making the memory use the second potential is reading the first data from the memory by making the memory use the second potential after the error detection and correction of the first data read by using the first potential is failed. 
     
     
       9. The method according to  claim 8  further comprising executing refresh of the first data at least on the basis of whether or not the error detection and correction of the first data read by using the second potential is failed. 
     
     
       10. The method according to  claim 9 , wherein the reading the first data from the memory by making the memory use the first potential is reading the first data from the memory by making the memory use the first potential periodically. 
     
     
       11. The method according to  claim 7 , wherein
 each of the multiple block groups includes two or more blocks, and the method comprising accessing the two or more blocks included in a same block group among the multiple block groups in parallel. 
 
     
     
       12. The method according to  claim 11 , wherein
 the memory includes first and second chips, 
 the two or more blocks included in the same block group includes a first block and a second block, 
 the first chip includes the first block, and 
 the second chip includes the second block.